P1225 - Serum Ammonia as a Non-Invasive Marker of Esophageal Varices. A Systematic Review and Meta-Analysis

Deepak B Shivananda, MBBS¹, Ananya Prasad, MBBS², Vinay C. Bellur, MBBS³, Advaith N. Rao, MBBS², Adithya Sathya narayana, MBBS³, Druvadeep Srinivas, MBBS^4
1Bangalore Medical College, Bangalore, Karnataka, India; ²Ramaiah Medical College, Bangalore, Karnataka, India; ³Ramaiah Medical College, Bengaluru, Karnataka, India; ⁴Raja Rajeswari Medical College & Hospital, Bengaluru, Karnataka, India

Introduction: The rates of esophageal varices is increasing with the association of hepatic cirrhosis, this calls for new and non-invasive diagnostic modalities. While endoscopy remains the mainstay and the gold standard for diagnosis of esophageal varices, non-invasive modalities provide less painful options to patients. Our review aims to assess the reliability of serum ammonia as a diagnostic modality by a pooled meta-analysis.

Methods: A systematic search was conducted in Pubmed, Google Scholar and Scopus. A boolean expression was constructed to search the databases. Observational studies assessing the sensitivity and specificity of serum ammonia levels to diagnose esophageal varices were selected for the Meta-Analysis. The sensitivity (true positive rate), specificity (true negative rate), positive likelihood ratio and negative (LR+, or LR-, is estimated by the ratio of the proportion of positive, or negative, tests in the diseased versus no-diseased subjects) and diagnostic odds ratio (DOR is calculated as the LR+ divided by the LR-), with a confidence interval (CI) of 95%, were obtained for each study and subsequently combined. Cochran Q chi-square test and the I^2 statistic were explored to assess the heterogeneity of the included studies. Random-effects model was used if the result of the Q test was significant (p< 0.05) and I^2 >50%. Pooled sensitivity , specificity and DOR were considered to be the primary outcomes of the meta-analysis.

Results: The study included 6 Articles with 948 subjects. The pooled sensitivity and specificity for diagnosis of esophageal varices was 92.5% ( 76.5% to 97.9%) and 89.1% (70.8% to 96.5%) respectively with 95% CI. The positive LR and the Negative LR was 8.506(-.304 to 17.352) and 0.084(-0.015 to 0.182) respectively.The pooled DOR was calculated to be 101.611( -27.981 to 231.203) . The random effects model was used as there was substantial heterogeneity in the study with I^2 of 69% and 52% for sensitivity and specificity respectively.

Discussion: Our pooled meta-analysis of serum ammonia levels as a non-invasive diagnostic tool to detect esophageal varices showed high sensitivity and specificity rates, making this tool a valuable addition during investigations for esophageal varices in hepatic cirrhosis. With high rates of sensitivity, specificity, and diagnostic odds ratio serum ammonia levels as an investigation should be explored and considered in the protocol for diagnosis of esophageal varices.



Disclosures:


Deepak B Shivananda, MBBS¹, Ananya Prasad, MBBS², Vinay C. Bellur, MBBS³, Advaith N. Rao, MBBS², Adithya Sathya narayana, MBBS³, Druvadeep Srinivas, MBBS⁴. P1225 - Serum Ammonia as a Non-Invasive Marker of Esophageal Varices. A Systematic Review and Meta-Analysis, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.